Fiber optic flow and oxygenation monitoring using diffuse correlation and reflectance

Abstract

Disclosed are fiber optic devices and related methods that allow for measurement of blood flow and oxygenation in real time. These devices have particular application to the spinal cord. Such devices have applicability in, for example, the care of military members sustaining combatant and noncombatant spinal injuries, as well as to civilians. The devices also have utility in the acute and subacute management of spine trauma, enhancing the efficacy of interventions aimed at the prevention of secondary ischemic injury, and ultimately improving neurologic outcome.

What is claimed: 
     
       1. A device, comprising:
 a first illuminator fiber having a longitudinal axis and having a distal end; 
 a first detector fiber having a distal end; 
 a tubular housing having a distal end, the tubular housing at least partially enclosing the first illumination fiber and the first detector fiber, 
 wherein the distal end of the first detector fiber is at a different location, as measured along the longitudinal axis of the first illuminator fiber, than the location of the distal end of the first illuminator fiber 
 the first illuminator fiber being in optical communication with an illumination source configured to supply illumination from the first illuminator fiber at from about 600 nm to about 970 nm, 
 the first detector fiber being in optical communication with a first illumination detector, and 
 the device being adapted for insertion into the spinal epidural space, the spinal intrathecal space, or both of a subject. 
 
     
     
       2. The device of  claim 1 , further comprising a computer processor in communication with the first illumination detector, the computer processor being adapted to estimate, based on illumination received by the first illumination detector, blood oxygenation, oxy-hemoglobin, deoxy-hemoglobin, blood flow, oxygen metabolism, water content, lipid presence, tracer presence, or any combination thereof. 
     
     
       3. The device of  claim 2 , wherein the computer processor is adapted to estimate blood flow, based on illumination received by the first illumination detector. 
     
     
       4. The device of  claim 3 , wherein the computer processor is adapted to estimate blood flow at a tissue depth of up to 2 cm, based on illumination received by the first illumination detector. 
     
     
       5. The device of  claim 2 , wherein the computer processor is adapted to estimate blood flow based on illumination received by the first illumination detector. 
     
     
       6. The device of  claim 1 , further comprising a second detector fiber, the second detector fiber having a distal end located at a different location, as measured along the longitudinal axis of the first illuminator fiber, than the location of the distal end of the first illuminator fiber. 
     
     
       7. The device of  claim 6 , wherein the second detector fiber is in communication with the first illumination detector. 
     
     
       8. The device of  claim 6 , wherein the distal end of the first detector fiber is located at a different location, as measured along the longitudinal axis of the first illuminator fiber, than the distal end of the second detector fiber. 
     
     
       9. The device of  claim 8 , wherein the distal end of the first detector fiber and the distal end of the second detector fiber are separated, as measured along the longitudinal axis of the first illuminator fiber, by a distance in the range of from about 0.1 to about 20 cm. 
     
     
       10. The device of  claim 1 , wherein the distal end of the first detector fiber and the distal end of the first illumination fiber are separated from one another by from about 0.01 to about 20 cm, as measured along the longitudinal axis of the first illuminator fiber. 
     
     
       11. The device of  claim 1 , wherein the illumination detector comprises a photodiode, an avalanche photodiode, a photomultiplier tube, a CCD camera, or any combination thereof. 
     
     
       12. The device of  claim 1 , further comprising a third detector fiber having a distal at a different location, as measured along the longitudinal axis of the first illuminator fiber, than the location of the distal end of the first illuminator fiber. 
     
     
       13. The device of  claim 1 , further comprising a second illuminator fiber, the second illuminator fiber having a longitudinal axis. 
     
     
       14. The device of  claim 13 , wherein the second illuminator fiber supplies illumination that differs in wavelength from illumination supplied by the first illuminator fiber. 
     
     
       15. The device of  claim 13 , wherein the second illuminator fiber has a distal end located at a different location, as measured along the longitudinal axis of the first illuminator fiber, than the location of distal end of the first illuminator fiber. 
     
     
       16. The device of  claim 15 , further comprising a second detector fiber, the second detector fiber comprising a distal end at a different location, as measured along the longitudinal axis of the second illuminator fiber, than the location of the distal end of the second illuminator fiber. 
     
     
       17. The device of  claim 1 , wherein the illumination source comprises a laser. 
     
     
       18. The device of  claim 1 , wherein the illumination source is configured to provide illumination at two or more wavelengths. 
     
     
       19. The device of  claim 1 , wherein (a) the distal end of the first illuminator fiber and the distal end of the first source fiber extend beyond the distal end of the tubular housing or (b) the distal end of the first illuminator fiber and the distal end of the first source fiber are enclosed within the tubular housing. 
     
     
       20. The device of  claim 19 , wherein the housing has a diameter of up to about 5 mm. 
     
     
       21. The device of  claim 20 , wherein the housing has a diameter of up to about 2 mm. 
     
     
       22. The device of  claim 21 , wherein the housing has a diameter of less than about 1 mm. 
     
     
       23. The device of  claim 19 , wherein one or both of the distal end of the first illuminator fiber and the distal end of the first detector fiber is disposed within the tubular housing. 
     
     
       24. The device of  claim 1 , wherein the first illumination fiber, the first detector fiber, or both is adapted for placement in the spinal epidural space, the spinal intrathecal space, or both. 
     
     
       25. The device of  claim 1 , further comprising a computer-readable medium having computer-executable instructions, wherein the computer-executable instructions calculate a correlation function. 
     
     
       26. The device of  claim 1 , wherein oxygen metabolism is measured using a bulk overall technique. 
     
     
       27. The device of  claim 1 , wherein the illumination source is adapted to provide illumination having a wavelength in the range of between about 600 nm and about 900 nm. 
     
     
       28. The device of  claim 27 , wherein the illumination source is adapted to provide illumination having a wavelength in the range of between about 600 nm and about 700 nm. 
     
     
       29. The device of  claim 1 , the device further comprising a fiber optic probe integrated with the first illuminator fiber and first detector fiber. 
     
     
       30. The device of  claim 1 , wherein the device is adapted for insertion into the subdural space of a subject. 
     
     
       31. The device of  claim 1 , wherein the device is configured to interrogate tissue at a depth of up to about 2 cm from the first illuminator fiber. 
     
     
       32. The device of  claim 1 , wherein the device is adapted for insertion through a needle into a subject. 
     
     
       33. The device of  claim 1 , wherein one or both of the distal end of the first illuminator fiber and the distal end of the first detector fiber is capable of direct optical communication with a tissue of a subject. 
     
     
       34. The device of  claim 1 , wherein the distal end of the first illuminator fiber and the distal end of the first detector fiber are in direct optical communication with one another.